The genuine realist, if he is an unbeliever, will always find strength and ability to disbelieve in the miraculous, and if he is confronted with a miracle as an irrefutable fact he would rather disbelieve his own senses than admit the fact.
 Fyodor Dostoyevsky, The Brothers Karamazov (1880). copy citation

Context

“but I fancy that Alyosha was more of a realist than any one. Oh! no doubt, in the monastery he fully believed in miracles, but, to my thinking, miracles are never a stumbling-block to the realist. It is not miracles that dispose realists to belief. The genuine realist, if he is an unbeliever, will always find strength and ability to disbelieve in the miraculous, and if he is confronted with a miracle as an irrefutable fact he would rather disbelieve his own senses than admit the fact. Even if he admits it, he admits it as a fact of nature till then unrecognized by him. Faith does not, in the realist, spring from the miracle but the miracle from faith. If the realist once believes, then he is bound by his very realism to admit the miraculous also.” source